In the production of signatures, a plurality of webs are printed on one or more presses to provide ribbons to be utilized in forming the signatures. The ribbons are typically delivered to a common point for ribbon merger after the webs have been printed on the presses. By merging the ribbons at the common point, a composite is provided which is then utilized in forming the signatures for gathering on a binding line.
In some cases, it is quite well known that it is particularly difficult to produce a signature that is entirely wrinkle-free. This is especially true in the case of closed end signatures wherein the signature has a head fold with a lead edge forward of the head fold and a trail edge rearward of the head fold. More specifically, gusset wrinkles in closed end signatures have been a serious ongoing problem in the printing industry for decades.
In this connection, the problem is difficult to solve in view of the variables that are encountered in the production of signatures. It is known, for instance, that the size of the signatures, i.e., the number of pages, and the different paper stocks that are run on presses, have significant variations which, among other things, would make it difficult for signatures without closed ends to be handled in both the press room and the bindery. Nevertheless, it is believed that the entirely closed signature end is what contributes most significantly to wrinkle production.
In addition, there are significant problems inherent in the environment of the press room and bindery in terms of material handling systems. It is especially important that any attempt to solve the wrinkle problem take into consideration the manner in which signatures are handled in both settings. More to the point, the signatures must remain stable if they are to be capable of handling by automated material handling systems.
As is known, the gusset wrinkle problem has only been exacerbated by the addition of automated material handling systems. This result has also followed from the fact that there are presently much wider web presses in service that produce large page counts for individual signatures, e.g., the average page count per signature is up from 48 pages several years ago to 64 pages today. Additionally, the gusset wrinkle problem has been further exacerbated by the fact that there are increased press speeds.
As for the effect of the wrinkles on the finished product, it varies from illegible type to advertisements that are unappealing to the eye. Numerous efforts have been made to overcome the problem, some of which have had a slightly positive effect, i.e., reducing the size and location of the wrinkle, but to date there has been nothing available that eliminates the gusset wrinkle in the finished product. As a result, the present invention is directed to overcoming this problem by making it possible to produce a wrinkle-free signature.